Field of the Invention
The present invention relates to an object information acquisition apparatus.
Description of the Related Art
As one in vivo imaging technique using near-infrared light, there is photoacoustic tomography (PAT). In PAT, an object such as a biological body is irradiated with pulsed light generated from a light source, whereby light propagated and diffused within the object is absorbed by a light absorber to generate an elastic wave. This mechanism of elastic wave generation is called a photoacoustic effect. Since a tumor has a higher light energy absorption rate for near-infrared light than surrounding tissues, the tumor absorbs more light than the surrounding tissues. Thus, the tumor momentarily expands and generates an elastic wave.
In an apparatus described in Japanese Patent Application Laid-open No. 2011-245277, the elastic wave is detected with a detection element and converted to a received signal. Through signal processing (reconstruction) of the received signal, object information such as the space distribution of initial sound pressure of the elastic wave generated upon absorption of light energy within the object can be imaged. Since the space distribution of generated sound pressure relates to the absorption coefficient of light, diagnosis of an object using space distribution relating to the absorption coefficient of light has been studied.